The term 'necktie fabric' can be broken down into two crossword solutions: SILK (4 letters) and REP (3 letters). SILK is a luxurious, natural fiber that is produced by certain insects. It is known for its softness, strength, and shine, making it a popular choice for neckties. REP is a type of fabric made from cotton or wool that has been woven with a pattern of raised cords. It is often used to make neckties due to its durability and texture.